1. Technical Field
The present invention relates to an image forming apparatus and an image forming method configured to prevent image-quality degradation when performing a screening process on image data.
2. Related Art
Electro-photographic image forming apparatuses have been known in which a latent image is formed upon an image bearing member (photoreceptor) using an exposure head provided with two or more light-emitting elements and an imaging optical system that forms the light from those light-emitting elements into an image. Technology that uses a lens whose optical magnification is negative (ML, or “minus lens”) is being developed as such an imaging optical system. JP-A-2008-049692 discloses a line head that uses an ML as its imaging optical system and an image forming apparatus that uses that line head.
In an image forming apparatus that uses a lens array including MLs (MLA), temperature differences arise within the MLA due to rises in the temperatures of the light-emitting elements. Accordingly, unevenness in the darkness of a printed image caused by unevenness in the light intensity occurs when performing a screening process on image data, resulting in degradation of the image quality. Furthermore, there are cases where image-quality degradation occurs due to pitch misalignment between light-emitting elements. In JP-A-2008-049692, there is no mention of measures to be taken in such a case.